A successive approximation analog-to-digital converter (Successive Approximation Analog-to-digital converter, referred to as “SAR ADC” for short) is a device that converts an analog signal into a digital signal.
A capacitive SAR ADC is a common SAR ADC, and accuracy of the capacitive SAR ADC is correlated with a total capacitance therein. Currently, if a capacitive SAR ADC is required to output an output result with an accuracy of an N-bit binary encode, two capacitor arrays consisting of N+1 capacitors need to be included. Capacitances of the capacitors in the capacitor array are in an exponential relation. Specifically, capacitances of the N+1 capacitors in the capacitor arrays meet the following relationship:
                    {                                                                                                                        C                      1                                        =                    C                                    ,                                                                                                                                                C                      n                                        =                                                                  2                                                  n                          -                          2                                                                    ⁢                      C                                                        ,                                                            N                      +                      1                                        ≥                    n                    ≥                    2                                                                                ,                                    (                  Formula          ⁢                                          ⁢          1.1                )            where C denotes a unit capacitance. Therefore, a total capacitance in one capacitor array is 2NC.